Hip replacement patients with metal-on-metal (MoM) implants (both the socket and hip ball are metal) pass metal ions to their infants during pregnancy, according to a new study presented today at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS). Data showed there is a correlation between cobalt and chromium levels in the mother and those in her infant at the time of delivery.
"Although the affects of metal ions in maternal and fetal subjects are unknown, the fact that the placenta is not a complete barrier to the transport of these metals is noteworthy," said Joshua J. Jacobs, MD, Professor and Chairman of Orthopaedic Surgery at Rush University Medical Center in Chicago. "As metal-on-metal implants increase in popularity and use, especially among young, active patients, women of child-bearing age and their doctors should be aware of these findings when considering their hip replacement implant options."
Researchers evaluated three patients who had either a unilateral (only on one hip) MoM primary total hip arthroplasty or unilateral MoM hip resurfacing joint replacement and no other metal implant in the body. The implant group's metal ion levels were compared within the group, between mothers and their infants, and to those of a Control Group comprising seven women of child-bearing age (mean age of about 32 years) who did not have any metal implants and their infants.
For all subjects, maternal and umbilical cord blood was obtained at the time of delivery and tested for blood serum concentrations of titanium, nickel, cobalt and chromium using inductively coupled plasma mass spectrometry (ICP-MS), a highly sensitive technique that can detect trace amounts of metals in biological samples.
